Painful tooth post adhesive filling

[LizK]

I have a upper molar that was first filled when I was in my teens. For over 20 years it has caused pain on and off (mostly off) (assessed by xrays, the jaw bite etc) Part of the filling fell out a few years ago and the filling was replaced- it's a large filling. Then earlier this year part of the tooth chipped off and that was fixed. For the past week or so I have had marked sensitivity to heat and cold and quite severe pain last night. For ppersistant pain  over the counter painkillers would work and it would often be 24 hours before I needed them again for persistant pain. I saw my dentist today and his assessment was that the tooth dentine is being exposed from incorrect brushing- and he placed a adhesive filling at the area. I am confident he is right. However he told me to use a tooth paste for sensitive teeth and leave some paste on the tooth overnight and if I was still in pain in 2 weeks to come back.
I asked when I could eat and he said it would be allright in 30 min (allowing for fluoride treatment to work). It was probably at least 2 hours before I had something. When the local wore off the gum area was quite painful.
However I have noticed a very small "something in my mouth - approx 4mm wide and transparent and then stringy stretchy tan  stuff coming away from the area.  I suspect this may be the adhesive used. The tooth itself is now sensitive in the upper area and not in the gum area.
Does this sound that my assessment could be correct? Should I wait 2 weeks and just keep using painkillers and see or get back to him ASAP. The painkillers work but when they wear off the pain is the same-its never been this constant.